NOTE: despite what the proc's description says, it actually hits *everything*, not only dragons.
Proc's base damage is 1000, +7000 vs dragons and +10,000 vs anything with Ultimate Loot Lair loot. Proc's rate is about 5%, with the usual boost of x20.5 with 20 hit, resulting in a whopping 369,000 proc and average damage increase of ~1k per 1 hit vs dragons from a single piece of this gear.
I. The ancient war between dragons and men was fought by tens of thousands, but it was brought about by just three. Erebus, Nalagarst and Echidna yearned to rule over the races of West Kruna, and it was they who turned the wyrms' minds towards such wicked ends. Of those bringers of carnage, Nalagarst met justice for his malevolence the quickest. He was slain in battle, slaughtered by the conflict he had so desired. But Erebus and Echidna lived on.
II. It wasn't cowardice that ensured Echidna's survival, for she threw herself into battle with all the fierceness of her draconic nature and murderous soul. She clashed with great heroes and demi-gods, led charges against legions of bold warriors. But though she was struck many thousands of times, her scales pierced by blade and arrow, spear and spell, the wounds healed long before they could claim her life -- sealed by forces far greater than the might of her foes.
III. When she was little more than a whelp, Echidna had roamed the skies of Tor'gyyl -- traveling the world to see what mysteries distant shores might hold. That odyssey brought her to the land of Bhanipur. There she soared above the palaces of nabobs and the mud huts of peasants, over jungles teeming with beasts and rivers on which corpses floated out towards the sea. Until she heard the playing of sitars, and the words of a song so lovely she couldn't bear to leave it unfinished in her memories. Echidna landed, that she might curl up before the bard and let the music wash over her.
IV. It was no mortal whose song she had heard. Ukshmi, whom some call divine and others infernal, sat in a field -- playing three sitars with her many arms, singing with a voice that danced in Echidna's soul. Ukshmi smiled when the dragon say before her, and continued to weave her song to the delight of her draconic listener. So when enemies came upon her, servants of a god who despised Ukshmi, Echidna fought at her side. For all the powers their master had lent them, the humans were slain. And Ukshmi offered the dragon a reward for her aid.
V. Ukshmi asked Echidna a strange question: whom might a dragon trust most in the world, her mate or her children? Echidna had neither mate nor whelps, but she told Ukshmi that a mother could always trust the love of her offspring -- though that of mates was fickle. Ukshmi laughed, and spoke the words of prophecy: "Dragon of the west, know that no violence shall ever claim your life, unless it comes from the claws of your children."